Modern and multi-step vehicle transmission in industrial vehicles have a multi-step main transmission part, an auxiliary-section transmission part and/or one multi-step splitter transmission part. With a splitter transmission the gear steps of the main transmission can be further split in their ratio so that lower ratio ranges result in successive gears. With an auxiliary-section transmission the total ratio of the main transmission, can be increased by it being possible to use all gear steps of the main transmission together with each gear step of the auxiliary-section transmission and in at least one gear step of the auxiliary-section transmission, to step up or down the otherwise direct ratio of the gear steps of the main transmission.
Such a vehicle transmission has been disclosed, for example, in DE 44 22 900 A1. These vehicle transmissions are mostly manually switched in the main transmission part while the switchings in the splitter transmission part and in the auxiliary-section transmission part result by a pneumatic or hydraulic actuator after a corresponding switching has been triggered by the driver. An automated switching device for vehicle transmissions of the kind mentioned above has also been disclosed such as described in EP 0 541 035 B1. Here are combined side-by-side in a control unit actuators of which one actuator operates the splitter transmission part, the main transmission part and the auxiliary-section transmission part. Each one of said actuators engages the ratio steps via a switching rod upon the respective switching devices. Each transmission part having to be operated by a separate actuator with appertaining valves, sensors and switching rods is a disadvantage here. This involves a great multiplicity of parts and the costs and heavy weight related therewith.
The problem on which the invention is based is to show a switching device for a vehicle transmission which simplifies the actuation of the auxiliary-section transmission part.